Help in Halo 3 forge?

[Melissa N]

hey i need help in halo 3 forge. my friend showed me a map on last resort and he gets on the roof using teleporters. i am always running into invisible walls and i am getting frustrated. i was wondering how you can get "outside the map"

 

[ryan_elkrem]

if you put a turret so the trigger is touching the wall, then you get on the turret so u are able to shoot with it. then you look the farthest up you can and then go into editor mode... you should go out of the map.